1. Technical Field
The present invention relates to a construction of a stator for use in dynamo-electric machine including alternator for vehicles.
2. Background Art
Generally in conventional stators for dynamo-electric machine, a plurality of teeth are disposed at the inside perimeter of a cylindrical magnetic member, and coils are disposed inside the slots formed between the teeth. In such a construction, coil insertion is a rather complicated work, and it is difficult to dispose high-density coils in the slots.
To cope with this problem, a method has been proposed, for example, in the Japanese Patent Publication (unexamined) No. 103052/1997. To make easy the coil insertion work and the disposition of high density coils in slots, this known method proposed that a rectangular parallelepiped-shaped laminated body is arranged by laminating plate-type magnetic members, each having a plurality of teeth on one side of a yoke portion, and after inserting the coils into slots formed between the teeth thereof, the laminated body is annularly bent with the coil disposition side inward.
FIG. 33 is a front view of a conventional type stator for dynamo-electric machine of this type. FIGS. 34 (A) and (B) show a manufacturing process of the stator for dynamo-electric machine shown in FIG. 33. FIG. 34 (A) is a front view before inserting coils and FIG. 34 (B) is a front view after inserting the coils.
In the drawings, numeral 1 is a stator core formed in such a manner that a rectangular parallelepiped-shaped laminated body 3 is formed into one piece by laminating a required number of plate-type magnetic numbers 2, each having a plurality of teeth 2b on one side of a yoke portion 2a, and then is annularly bent so that both ends are brought into contact with each other and then fixedly connected by welding. Numeral 4 is coils inserted and disposed through slots 2c formed between the teeth 2b. 
Referring now to the drawings, a manufacturing process of the conventional stator for dynamo-electric machine of the above-mentioned construction will be hereinafter described.
First, a required number of plate type magnetic members 2, each having a plurality of teeth 2b on one side of a yoke portion 2a, are formed by punching and then laminated and joined together to form a rectangular parallelepiped-shaped laminated body 3. Then, after inserting and disposing the coils 4 through the slots 2c thereof as shown in FIG. 34 (B), the laminated body 3 is annularly bent by a molding machine (not shown) so that both end portions are brought into contact with each other and then fixedly integrated by welding. Thus, a stator for dynamo electric machine is manufactured.
In the conventional stator for dynamo-electric machine having such a construction as described above, because a laminated body 3 is bent after inserting the coils 4 therein, it is certainly possible to conduct easily the coil insertion work and dispose the coils 4 with high density. However, the yoke portion 2a is required to have a certain thickness to secure a necessary cross sectional area for magnetic path and, therefore, a stronger power is required to bend annularly the laminated body of large thickness. Consequently, a problem exists in that an air gap is formed between both end portions as shown in FIG. 35, and it is difficult to obtain a structurally perfect circle. Moreover, a further problem exists in that the laminated body 3 is distorted to the extent of decreasing magnetic performance, eventually resulting in deterioration of efficiency.